Projection apparatus



Jan. 26, 1932.

c. E. RANDALL ET AL 1,842,840

PROJECTION APPARATUS Filed Sept. 28, 1929 /N VE N TORS Cir/7 frnesr Randall ATTORNEYS Patented Jan. 26, 1932 cYnIL nnnnsr RANDALL, or LONDON,

Lonnon,.'n-NeLANn;.assrenons 'rotao'rm c j rrtbano'rron i mates Application filed September 28, 1929,'Se ria1.1to.

This invention comprises improvements in and connected with methods of and means for projecting light and other radiations and is concerned with a class of projectionapparatus in which the rays from alhigh intensity source are received by a projection mirror or reflector and reflected on to a-mosaic of mirrors eachof which is appropriately angularly adjusted or adjustable for diverting apertion of saidbeam in a given direction. Thus the mirrors maybe adjustedfor projection on to the screen of spots of light disposed along lines forming characters and in this way advertisements and signs may lee-projected on to clouds and. other distant screens.

Methods and apparatus for the projectionof luminous signs on to distant screens of the character aforesaid have formed the subject of Patent No. 1,750,785 and of copending application Serial No.'-365,505. Known'forms of apparatus have-however suffered limitations-,- particularly in regard to the amount of light available for distant projection, the light having been obtained from one arcdight or, at the 1IlOSl],'tWO. Furthermore, limitations of an important character were imposed by diificultiesconnected with the projection reflectors Whichare neither practical nor economical beyond certain restricted diameter.

Attempts to increase the brilliance of the luminous image have moved in the direction of employing a larger source of light and a proportionately longer focus projection mirror, the idea being to project an imageof the arc of the same size as before but of increased brightness. Apparatus constructed for this purpose becomes unwieldy for the projection. mirror and the mirrors of the mosaic must be of greater dimensions and projeetion mirrors of the diameter required are not readily obtainable commercially.

Furthermore the method previously proposed for altering the elevation of the beams reflected by the mosaic Where a mosaicof plane mirrors is so arranged as to maintain its angle of inclination relative to the axis of the projection mirror and light source but is rotatable so that the deflection of the rays may take place. in a substantially: verticalplane,

AND rlnzj jiennnoisnnr'rnonrson, or 'HENDON,

Lihronnsiev'zienor ennon, ENGLAND 335,970; and: in: Great Britain- .October 3, 192a.

oranaybe swung down to a horizontal plane, orinternre diately, thus giving a variable inclinationof theluniinous image on the screen, has a defect in thatone cannot guarantee that ,everyguniti portion. of g the projection mirror regarded as a seriesof rings from successive parts. :of which-:1 any mirror in the mosaic picks up its "illumination during the translation, from a. K verticalfto horizontal throw, is initself regular and thus the delicatc ande iact coadjustment of projection mirror and;iiiosaLGis liable to be thrown out by the; ecessary actionof altering the angle oiielev H enofthe display.

iilnrhddition. i is rotatable. mirror mosaic is, ow ngto-its large size and diifieult mechanical eontruction, a, particularly heavy piece of mechanism. andpannot readily bev exchanged lop another, mirrorvmosaic to change the form of-the sign on other image projected.

,fury;attempttojnerease the brilliancy of the linninons image thy enlarging the crater ofstheiarc and iisinga longer focus projection mirrorlpmduces an aggravation ofthis defect ofweight andleads to. an impracticable design and enhanced cost of construction.

According-tea feature of this invention, two or more sources of light or other radiations are einployed eaclrin conjunction with its own: projection-reflector and with its own respective mirror. assemblage or mosaic adaptedfor receivingrays reflected by the projection. mirror, or reflector and all the mirror assemblages are adjusted in a similar mannersoihat at a predetermined distance fromithe apparatus the radiations projected by corresponding mirrors of each assemblage melt ,ivherebyin the case of light rays a luminoussigir of greatly increased brilliance is. produced upon a screen located at the point of coincidence. In the case of. the formation of a luminous image ona distant screen such projection mirror or reflector may be searchlight reflectorofv the spherical or parabelie type andtheinosaics may be composed of plane concave or convex mirrors arranged nearwto the-respective source and projection n'iirror or reflector and across the path of the reflectedrrays which are completely interccpted by the mosaicr Any-onemirror of distant screens may be of"increase d bril-"l liance and sharply defined owing to the con joint effect of several sources of illumina tion each being employed in combination with pieces of apparatus which-are of handy size and easily mounted and manoeuvred. The 'imp'roved effect, also,- is due to the fact that better optical effects can be-obtained and less expensi've opt-ical elements used when thelightprojection means are split up into re apses-Ive units instead of being embodied in, one single large unit.

It is-important in the apparatus of the present invention that there be 'a rigid co-adjustment of the three optical components of a unit, namely the source of light or other radiations, the projection mirror or reflector and "thefasseniblages of mirrors during pro j'c't'ion, and'a'lso' a rigid relative adjustment of the units themselves, for'the setting given to the numerous-mirrors of such assemblages must-nobbe disturbed during adjustments for 'alte iii'g the elevation of the projection. Inother words, although two, three, four or any honvenient' number of sources of radiaoils maybearranged each with its projection inirrort'o-produce separate beams of light or other radiations they are all rigidly fixed-to a common frame and the resultant beams fall upon mirror mosaics which are all on oneframe and which can be set up and operated-in ,exactly'the same way as if they were one tch of mirror mosaic opposite to one lamp one reflector.

In addition, the present invention provides a's'imple and convenient way of substituting one set of mosaics or assemblages for anothorfso as to permit in the case of the formation of a: luminous sign on a screen of the foi-iir of the luminous outline being readily varied. The whole construction is compact,

and: in proportion to its power, light and portable.

In order that the present invention may be clearly understood and readily carried into effect: reference may now be had to the accompanying drawings diagrammatically illustrating one embodiment of the invention and in which;

Figure 1 isa perspective view ofthe principal parts of anapparatus according to the relatively invention; 'QFigur'e 2 is a side elevation view of the apparatus shown in Figure 1;

Figure 3 illustrates a mode of mounting each'mirrorof the mirror mosaics;

chassis z8 is' of'veryrigid construction :and is reel-table by suitable means, preferably so that a-variatiou from the horizontal of in each direction may be obtained with accuracy. Thus, the chassis 8 may be suitably counterweighted if necessary and may be operated in any -'convenient manner either manually or automatically such forinstance as through a combination of cables, pulleys andscrew' gear for-securing the desired adjust-ment- -WVhere cables-are used it is advantageous to'anchor them at each end ofthe frame 'or-chassis 8 and to impart the pull by means of screwgear operating through the medium of equalizingpulleys. .In-this Way the two sidesof'the chassis 8 are operated upon equally and there is no tendency to cant. f

The principalconstructional features of the chassis are two main girders Q of exceptional strength and rigidity, having regard to the nature of the structure, and tensien'and compression members '10 arranged transversely for bracing themain girders 9 and producing a rigid frame. Onehalfof the framep8-i's on one side of the-roclrer hearing and. serves for supper the light sources 11 and projectionrcfiectors 12, the other half on the opposite of such bearing serves for s pporting the assemblagesor mosaics-of mirrors 13. In the drawings three light sources and their rojection reflectors are shown and these are all mountedrigidly so that their-optical axesarc in accurate parallelism. Thus, they all'be mounted in a rigid metal framework forming part of a lamp house 14- fittcd with appropriate chimneys or vents 1.5 and bolted down on the rockable chassis. At the opposite end of the frame on the opposite side of the rocker bearing, there are erected two standards 16 fitted with half bearings not shown and made rigid for instance by means of'struts and bracings'. These half bearings receive the trunnions or aX-lcs lrof'a framework 18 designed for supporting panels or.framesvl9 on which are mounted the numerous adjustable mirrors 20 formingthe three assemblages or mosaics for fro-operation with the three optical units. The-panels 1'9 may-be removably mounted on the frameworir so that they can be interchanged with facility. Also, sets of panels mirrors to' throw the bac'l; to d andji'over the lamp hou. angl o v, about 6Qdegrees. Th I ping'fthe whole mirror panel boarlatlan angle may be conveniently about de atan angle of degrees with} the main girders. v

Each mirror panel 19 may consist of; a shallow tray constructor inone piece adapted to be bolted on the front or baclrofthe frame andcarryii g front and facing sheets oi suit} able material wh ch maybe thick ply xvo'odor any material thatislight 'and' rigid 1n the form'of sheets. The areas onjwh ch the rays from the lam )s and mirrors fall a-ie'covered with )lane reflectin mirrors 20 ofsuitable l .h f

size a'nd each mounted so' that they may be ad usted accurately by t pping to produce the necessarydeflections of tl e image bea mg rays from the lamp house andthus syi thetize the signer device required o n thej One manner ofmountmg the inscreen. dividuatmirrors 9.0 of the mirror mosaics s illustrated in Figureji in which the mirror 20 is shoivn as held to the panel 19 by its centre point by the spring 21 actedupon by three screw elements 22 coopeating th suitable bosses on the panel.

An obvious variation of the reversible frame is the provision of a 3, e, 5 or 6 sided drum mounted to turn in the same way, each side of the drum fit-ted ivith a full complement of mirror mosaic panelssuitablyjsecured and having its mirrors adjusted for the production ofa given sign or display. In Figure 4 a hexagonal frame 23 is shown on each face of which the appropriate number of mirror mosaics is adapted to be detachably secured. To accommodate the panels the faces of the frame may be recessed at 24 and the panels may be detachably secured in any convenient manner on the shoulders 25., The hexagonal frame is of course adapted for r0 ration such a manner as to bring any one of its faces into cooperative relation With-the beams of light.

The projection reflectors or mirrors to be employed are preferably good quality searchlight reflectors which should be of such a diameter and focal length as to produce a sign of the dimensions required.

These reflectors should have an angle of inin their housings so that they maybe quickly I and removed for 'clean'ing to prevent i ype ed eae neously.

projection. .reflefctor or mirror is ,lproduced.

are moist, advantageously of the type adapted to burn stea' dily witli a ratherlong arc.

Current for the light source may be fed in through the centering device and turntable bearing from sliprings mounted beneath the foundation or.from copper on the foundation on which track brushes the turntable make contact.

The controls of all, the light, sourcesmay be or, slippers on broughtout, together atone side ofthe lamp house so' that ,-they, may .beoperated conveniently by one attendant.,,

All thefmecha Teal movements of the projector .e.' rotation.elevationand the changy the. seriQ-lls .inefiiciencypccasioned. by. the de; I 'p si 9 th gl slo' ii i e fi' 'm'th he rs i 'smavibe'ef the s and d 7 i h ithpawab carriers made sucha "lwa'y that; very little J I M I "obscuration ofthefr'ays,returning from the; atjan angle wit-litheaxis of theprojection;; i v

i QThey can ,be :convenientlyburned{in series; on parallel and should be adapted to 7 use high 'inteiisitjcheniically. cored carbons? at. H high current density to ptoducetheutmost v j Y brillianeyin .the cratersl The lightjsources he jxferticalbearingstandard, that to say,

mg of di'splays by' the. reversal of the. mirror mosaic frame lila-yli f desired be distantly controlled by relays and electric or other suitable drives attached at suitable-points so that an'observer remotely situated whois usually better. able to, judge the best direction in which toproject, may directly control the training ofthe apparatus.

When an apparatusas heretoforedescribed is used for the projection of a luminous sign on to a distant-screen the individual mirrors 20 oft-he mirrorass'emblages 13 are angularly posed to occupy a cross sectional area of one.

of said beams and means whereby selected pencils of rays from each assemblage all caused to converge to a common point a predetermined distance from said appai -tus.

2. Apparatus for projecting light and other radiations as claimed inclai ni l in which a common rockable frame is provided for all said assemblagesthereby enabling the direction of projection of the radiations from all said assemblagesto beadjustcd simultae signs on to distant screens compris ng combination a number of deyices disposed for projecting substantially parallel beams of- .fdriiiation are common area of ligl1t"onthe screen whereby a luminous ofincreased brilliance is obtained.

a. Apparatus; for projecting luminous signs"-onto distant screens asfclaimed in claim 3 ill "Which the said assemblages are mounted upon a "commoirtilt'able frame thcrebyenabling the position of the luminous sign on the screen to be changed.

or'Apparatus tor projeet'ing' light and ,other radiations comprising a chassis, means. ivhereby said chassis be roc 'd about a horizontal axis, a plurality of devices each capable of'projecting a substantially parallel bea i'n' of light or otherradiations mounted upon said chassis in such, a manner that the am "of the setreralbeams are substantially parallel, aplu'rality 0t assemblagesofoptical units mounted upo'n'said chassis and each disposed to'occupy a cross sectional area o'f one of said beams and means for adjusting said assemblages simultaneously forthe purpose specified. v

'5. Apparatusv for projecting light and other radiations comprising a chassis, means u'hcreby said chassis may be rocked about a horizontal aiiis, a plurality of devices each capable of producing a substantially par-ah lel beam of light or other radiations mounted upon said chassis in such wisethat the soeral beams procced'in thesa'me direction and 40 are substantially parallel to oncanothcr, a

framework mounted upon said ch in path ofsa'id beams', and aplurality oi as: blages of optical units n'iounteil upon. said framework so that each .n the path 0t o oi": said beams of light.

7. Apparatus for .projectin other radiations comprising a chassis, men for rocking said chassis about a horizons axis, a plurality of devices each capable of producing a substantially parallel beam of light or other radiations mounted upon said chassis in such Wise that the set-c -al beams proceed in the same direction and ar Sll a)" stantially parallel to one another, a of assemblages of optical units mounted on said chassis so that each is in the path 05 one of said beams, at least one a ditioual oi assemblages of optical units l means to able any one of such sets of assemblages to be brought into operative relation rith beams at .Will. I

8. Apparatus for projecting light and other radiationscomprising a chassis, means for roclting said chassis about horizontal axis, a plurality of devices each capable of on to distant screens producing a substantially parallel beam of' light or other radiations mounted upon said chassis in such Wise that said beams proceed "in the same direction and are substantially bination a chassis, a number of devices each capable of producing a substantially parallcl beam of light mounted upon said chassis, assemblages of mirrors mounted upon said chassis to occupy inclined cross sectional areas of respective beams oflight, means for individually angularly adjusting the mirrors of each assemblage and means to enablesaid chassis to be rocked about a horizontal axis.

10. Apparatus for projecting luminous signs on to distant screens comprising in com: bination a chassis, a number of devices each capable ofproducing'a substantially parallel 4 beam of light mounted upon said chassis, assemblages of mirrors mounted upon said chassis so that each occupies an inclined cross sectional area of one of said beams of light, means for individually angular-1y adjusting the mirrors of eachassemblage, means Whereby said chassis may be adjusted angularly about a horizontal axis and means whereby said chassis may be adjusted angularly about a vertical axis. 1

11; Apparatus for projecting luminous comprising in combinalion chassis,anumber of devices each capable of producing a substantially parallel beam of light mounted upon said chassis in such wise that said beams proceed in the same direction and are substantially parallel to one another, a framework rotatable about a horizontal axis mounted upon said chassis in the path of said beams at a predetermined ante from said devices, assemblages of mirrors mounted upon said framework '50 that each cooperates with a corresponding been of light, means for individual angular Iii;

means for angular-1y adjusting said a about a horizontal axis and means angular ad ustment of said chassis about t i ill.

assemblages of mirrors mounted upon said framework so blages of each set cooperate ponding one of said beams,

that the individual assem- With a corressa-id sets of assemblages being brought into operative relation with said beams at the Will ator.

of the oper- In testimony whereof we have signed our names to this speclfication. V

CYRIL ERNEST RANDALL.

LEO

NARD ROBERT THOMPSON. 

